Evolved distributed antenna system

ABSTRACT

One embodiment is directed to a distributed antenna system (DAS) including a host unit and a plurality of remote units. The host unit includes a plurality of base transceiver stations and a switch. Each of the base transceiver stations is configured to provide a downstream baseband digital signal to the switch and to receive an upstream baseband digital signal from the switch, wherein each downstream baseband digital signal and upstream baseband digital signal is a digital representation of the RF channel at baseband of the respective base transceiver station. The switch is configured to route each of the downstream baseband digital signals to a respective subset of the remote units as one or more downstream serial data streams and to route each of the upstream baseband digital signals from one or more upstream serial data streams to a respective subset of the base transceiver stations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/502,556, filed on Jun. 29, 2011, which is herebyincorporated herein by reference.

BACKGROUND

One way that a wireless cellular service provider can improve thecoverage provided by a given base station or group of base stations isby using a distributed antenna system (DAS). In a DAS, a representationof radio frequency (RF) wireless communication signals are communicatedbetween a host unit and one or more remote units. The host unitgenerates a downlink transport signal that is distributed to one or moreof the remote units. A remote unit can receive the downlink transportsignal and reconstructs the downlink RF signals based on the downlinktransport signal and causes the reconstructed downlink RF signals to beradiated from at least one antenna coupled to or included in the remoteunit. A similar process is performed in the uplink direction. RF signalstransmitted from mobile units (also referred to here as “uplinksignals”) are received at a remote unit. A remote unit uses the uplinksignals to generate an uplink transport signal that is transmitted fromthe remote unit to the host unit.

One or more intermediary devices (also referred to here as “expansionhosts” or “intermediary devices”) can be placed between the host unitand the remote units in order to increase the number of remote unitsthat a single host unit can feed and/or to increase thehost-unit-to-remote unit distance.

SUMMARY

One embodiment is directed to a distributed antenna system (DAS)including a host unit and a plurality of remote units communicativelycoupled to the host unit. The host unit includes a plurality of basetransceiver stations and a switch. Each of the base transceiver stationsis configured to operate on a radio frequency (RF) channel to provide adownstream baseband digital signal to the switch. Each of the basetransceiver stations is also configured to receive an upstream basebanddigital signal from the switch, wherein each downstream baseband digitalsignal and upstream baseband digital signal is a digital representationof the RF channel at baseband of the respective base transceiverstation. The switch is configured to route each of the downstreambaseband digital signals to a respective subset of the remote units asone or more downstream serial data streams and to route each of theupstream baseband digital signals from one or more upstream serial datastreams to a respective subset of the base transceiver stations.

Another embodiment is directed to a distributed antenna system (DAS)including a host unit and a plurality of remote units communicativelycoupled to the host unit. The host unit includes a baseband interfacebackplane having a plurality of backplane connectors, each backplaneconnector configured for insertion of a radio frequency (RF) channelmodule. The host also includes a switch configured to convert betweenone or more serial data streams for the remote units and basebanddigital signals, wherein the baseband digital signals comprise a digitalrepresentation of an RF channel at baseband. The host unit furtherincludes a first RF channel module inserted into a first of thebackplane connectors, the first RF channel module including adigital-to-analog RF transceiver to convert between an RF signal of abase station and a baseband digital signal. The host unit also includesa second RF channel module inserted into a second of the backplaneconnectors, the second RF channel module including a base transceiverstation configured to receive downstream Internet Protocol (IP) data andperform baseband processing on the downstream IP data to generate thedownstream baseband digital signal, and to receive an upstream digitalbaseband signal and perform baseband processing on the upstream basebanddigital signal to generate IP data.

Yet another embodiment is directed to a method for generating anddistributing wireless RF signals at a host unit in a distributed antennasystem comprising the host unit which is communicatively coupled to aplurality of remote units. The method includes receiving InternetProtocol (IP) data at the host unit, from an IP network entity, whereinthe IP data corresponds to a radio frequency (RF) signal. The methodfurther includes routing the IP data to a respective base transceiverstation within the host unit. The host unit can baseband process the IPdata at each base transceiver station such that each base transceiverstation generates a digital representation of an RF signal fortransmission from a remote unit to a wireless device, wherein thedigital representation of the RF signal is at baseband. The host unitcan also multiplex the digital representations of an RF signal togetherto form a serial data stream, and send the serial data stream from thehost unit to one or more of the remote units.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high level block diagram of a wireless communication networkincluding a distributed antenna system (DAS) with an integrated basestation subsystem.

FIG. 2 is a block diagram of an example host unit for use in the DAS ofFIG. 1.

FIG. 3 is a diagram of another example host unit for use in the DAS ofFIG. 1.

FIG. 4 is a diagram of yet another example host unit for use in the DASof FIG. 1.

DETAILED DESCRIPTION

FIG. 1 is a high level block diagram of a wireless communication networkincluding a distributed antenna system (DAS) 100 with an integrated basestation subsystem. The distributed antenna system 100 is communicativelycoupled to an Internet Protocol (IP) network 101 via one or morebackhaul links 103 and to a first one or more base stations 107 via oneor more base station links 109.

In the IP network 102 data is sent between entities using the InternetProtocol. Accordingly, the IP network 102 is a packet based network. Inan example, IP data (that is, packets of IP data) is communicatedbetween the DAS 100 and the IP network 102.

The IP network 102 can comprise carrier networks for one or morecarriers of wireless services, and the DAS 100 can be, for example,coupled to multiple wireless service providers' (i.e., carriers')networks within the IP network 102. The IP network 102 communicativelycouples the DAS 100 to other communication systems such as other basestations 105, the public switched telephone network (PSTN) 108, theInternet 110, the IP multimedia system (IPM) 112, and/or other networks.

IP data from the IP network 102 is provided to the DAS 100 forgenerating wireless RF communication signals for wireless devices.Likewise, the DAS 100 receives wireless RF communication signals fromwireless devices, and generates IP data corresponding to the wireless RFsignals. The IP data is sent to the IP network 102 over the backhaullinks 103 for distribution to the appropriate entity (for example, basestation 105, PSTN 108, Internet 110, IPM 112, and/or other network). Insome examples, the IP data from the IP network 102 can be converted to adifferent (for example, proprietary) structure for interfacing with theDAS 100.

Within the IP network 102, the backhaul links 103 can couple the DAS 100to one or more IP access gateways 114, such as a home node B (HNB) orhome evolved node B (HENB) IP gateway. An IP access gateway 114 caninterface the DAS 100 with the rest of the IP network 102 and provideaccess control to a carrier network within the IP network 102. Forexample, the IP access gateways 104 act as an interface between the DAS100 and a radio network controller (RNC) 116, serving gateway (S-GW)118, mobile management mobility (MME) 120, and serving general packetradio services (GPRS) support node (SGSN) 122. In examples where thebackhaul is trusted, an IP access gateway 102 may not be used and theDAS 100 can interface directly with another entity (other than the IPaccess gateway 102) within the IP network 102. In such an example, theDAS 100 can be coupled directly to the RNC 116, serving gateway 118, MME120, SGSN 122. The DAS 100 could also be coupled directly to other basestations 105.

Some example entities within an IP network 102 are shown. The exampleshown in FIG. 1 includes a mobile switching center (MSC) 124 and/orgateway mobile switching center (G-MSC) 126 to interface with the PSTN108. The MSC 124 and/or gateway MSC 126 can provide circuit-switching tothe public switched telephone network (PSTN) 108. The PSTN 108 can beused, for example, for voice communications. For example, one or morewireless devices (for example, mobile telephones, mobile computers,and/or combinations thereof such as personal digital assistants (PDAs)and smartphones) can make a voice call to a land line telephone via thePSTN 108. The IP network 102 can also include SGSN 112 and a gatewayGPRS support node (GGSN) 128 which provide an interface to the Internet110. The GGSN 128 can also connect to other networks such as a localarea network (LAN) or a wide area network (WAN). The IP network 102 canalso include a serving gateway 118, mobile management mobility entity(MME) 120, and PDN gateway 130 for interfacing with the IPM 112.

In the downstream direction, the DAS 100 is configured to receive IPdata (e.g., IP packets) from the IP network 102 (for example, via the IPgateway 114) over the backhaul links 103 and to generate and distributewireless communications signals for one or more wireless devices fromthe IP data. In the upstream direction, the DAS 100 is configured toreceive wireless communication signals at one or more antennas and toconvert the wireless communication signals into IP data representativeof the wireless signals for the IP network 102. In the exemplaryembodiment shown in FIG. 1, the DAS 100 generates and receives aplurality of bi-directional radio frequency bands. Each such radiofrequency band is typically used to communicate multiple logicalbi-directional RF channels.

In addition to the backhaul links 103, the DAS 100 can also be coupledto one or more base stations 107 via the one or more base station links109. Communication between the one or more base station links 109 canoccur as a radio frequency (RF) signal or as a baseband digital signalas discussed below. The one or more base stations 107 can be coupled tothe IP network 102 via another backhaul link 111. In the downstreamdirection, the DAS 100 can receive an RF or baseband digital signal froma base station 107 and distribute the signal signals for one or morewireless devices. In the upstream direction, the DAS is configured topass wireless signals corresponding to an RF channel of a base station107 from one or more wireless devices to the base station 107.

Notably, the DAS 100 can be configured to operate concurrently on bothdata that is upstream of the baseband processing, such as IP datacommunicated with the IP network 102, as well as signals that aredownstream from the baseband processing, such as the RF or basebanddigital signals from the base station 107. More detail on this isprovided below with respect to FIGS. 2-4.

The techniques described herein with respect to the DAS 100 areespecially useful in connection with wireless communications that uselicensed radio frequency spectrum, such as cellular radio frequencycommunications. Examples of such cellular RF communications includecellular communications that support one or more of the secondgeneration (2G), third generation (3G), and fourth generation (4G)Global System for Mobile communication (GSM) family of telephony anddata specifications and standards, one or more of the second generation(2G), third generation (3G), and fourth generation (4G) Code DivisionMultiple Access (CDMA) family of telephony and data specifications andstandards, and/or the WIMAX family of specification and standards. Inthe particular exemplary embodiment described here in connection withFIG. 1, the DAS 100 is configured to handle two cellular bi-directionalradio frequency bands. In other embodiments the DAS 100 is used withwireless communications that make use of unlicensed radio frequencyspectrum such as wireless local area networking communications thatsupport one or more of the IEEE 802.11 family of standards. In otherembodiments, combinations of licensed and unlicensed radio frequencyspectrum are distributed. In one embodiment, the DAS 100 is configuredfor use with a MIMO protocol. The DAS can be configured for use in atleast one of: in-building applications, outdoor applications, enterpriseapplications, public safety applications, and military applications.

In the exemplary embodiment described here in connection with FIG. 1,the DAS 100 is configured to generate and distribute wirelesscommunications that use frequency division duplexing to implement thelogical bi-directional RF bands. In other embodiments, the DAS 100 isconfigured to communicate at least some wireless communications that useother duplexing techniques (such as time division duplexing, which isused, for example, in some WIMAX implementations).

Since the DAS 100 is configured to use frequency division duplexing inthis exemplary embodiment, each of the bi-directional radio frequencybands distributed by the DAS 100 include a separate radio frequency bandfor each of two directions of communications. One direction ofcommunication is from the IP network 102 or base station 107 though theDAS 100 to a wireless device and is referred to here as the “downstream”or “downlink” direction. The other direction of communication is from awireless device through the DAS 100 to the IP network 102 or basestation 107 and is referred to here as the “upstream” or “uplink”direction. Each of the distributed bi-directional radio frequency bandsincludes a “downstream” band in which downstream RF channels arecommunicated for that bi-directional radio frequency band and an“upstream” band in which upstream RF channels are communicated for thatbi-directional radio frequency band. The downstream and upstream bandsfor a given bi-directional radio frequency band need not be, andtypically are not, contiguous.

In the exemplary embodiment shown in FIG. 1, the DAS 100 includes a hostunit 104 and one or more remote units 106. The DAS 100 shown in FIG. 1uses one host unit 104 and six remote units 106, though it is to beunderstood that other numbers of host units 104 and/or remote units 106can be used. As shown in FIG. 1 a remote unit 106 can be a destinationfor a downstream signal from the host unit 106 and can radiate awireless RF signal from an antenna associated therewith based on thedownstream signal. Such a remote unit 106 with an associated antenna isreferred to herein as a “remote antenna unit” or “RAU” and can functionto transmit/receive wireless RF signals over accompanying antenna towireless devices. Each such remote antenna unit 106 is communicativelycoupled to a respective antenna over a respective coaxial cable (such asa 50 Ohm coaxial cable). In some embodiments, a remote unit 106 isimplemented as a remote unit, such as an indoor or outdoor remote unitcommercially available from TE Connectivity. The remote unit is alsodescribed in U.S. patent application Ser. No. 11/627,251, assigned toADC Telecommunications, Inc., published in U.S. Patent ApplicationPublication No. 2008/0181282, and incorporated herein by reference.

A remote unit 106 can also be a distribution point that can receive adownstream signal from the host unit 104 and can provide furtherdownstream signals based on the downstream signal from the host unit 104to multiple other remote units 106. In one implementation of such anembodiment, groups of the remote units 106 are configurable for localjoint beamforming and/or joint transmission groups of cells.

In the exemplary embodiment shown in FIG. 1, the host unit 104 iscommunicatively coupled to the remote units 106 over a transportcommunication medium or media. The transport communication media can beimplemented in various ways. For example, the transport communicationmedia can be implemented using respective separate point-to-pointcommunication links, for example, where respective optical fiber orcopper cabling is used to directly connect the host unit 104 to eachremote unit 106. One such example is shown in FIG. 1, where the hostunit 104 is directly connected to some remote units 106 using arespective optical fiber 108. Also, in the embodiment shown in FIG. 1, asingle optical fiber 108 is used to connect the host unit 104 to theremote unit 106, where wave division multiplexing (WDM) is used tocommunicate both downstream and upstream signals over the single opticalfiber 108. In other embodiments, the host unit 104 is directly connectedto the remote unit 106 using more than one optical fiber (for example,using two optical fibers, where one optical fiber is used forcommunicating downstream signals and the other optical fiber is used forcommunicating upstream signals). Also, in other embodiments, the hostunit 104 is directly connected to one or more of the remote units 106using other types of communication media such a coaxial cabling (forexample, RG6, RG11, or RG59 coaxial cabling), twisted-pair cabling (forexample, CAT-5 or CAT-6 cabling), or wireless communications (forexample, microwave or free-space optical communications).

FIG. 2 is a block diagram of an example host unit 104 for use in the DAS100. The host unit 104 comprises a base station subsystem 201 that isintegrated together with a DAS subsystem 203 as a single entity. Thebase station subsystem 201 receives IP data from the IP network 102 andperforms baseband processing on the IP data to generate a digitalrepresentation of one or more RF signals to be wireless propagated to awireless device(s). The base station subsystem 201 also performsbaseband processing on digital representations of (wireless) RF signalsreceived from a wireless device and generates IP data based thereon forsending over IP network 102. Such a digital representation of an RFsignal comprises digital samples of the RF signal at baseband, and asignal including such digital samples of an RF signal at baseband isreferred to herein as a baseband digital signal. The digital samples canoptionally comprise in-phase digital baseband data and quadraturedigital baseband data. Accordingly, the base station subsystem 201outputs to, and receives from, the DAS subsystem 203 one or morebaseband digital signals. Notably, when generating a baseband digitalsignal from IP data, the base station subsystem 201 does not generate anRF signal. The base station subsystem 201 merely generates a digitalrepresentation of an RF signal and provides the digital representationas a baseband digital signal to the DAS subsystem 203. An RF signal isthen generated from the baseband digital signals downstream of the basestation subsystem 201, such as in a remote unit 106.

The DAS subsystem 203 receives the one or more baseband digital signalsin parallel from the base station subsystem 201 and forms one or moreserial data streams therefrom for transmission to the remote units 106.Such a serial data stream contains digital representations of an RFchannel. In an example, the digital representations of the RF channelare digital samples of the RF channel at baseband which correspond tothe digital samples of the baseband digital signals; however, in aserial stream the data is formatted for (high speed) serialcommunication to the remote units 106 as discussed below. In anotherexample, such a serial data stream contains intermediate frequency (IF)samples of the RF channel that are formatted for (high speed) serialcommunication to the remote units 106. In the upstream, the DASsubsystem 203 receives serial data streams from the remote units 106 andconverts the serial data stream into one or more (parallel if multiple)baseband digital signals for the base station subsystem 201. Asmentioned above, the base station subsystem 201 and the DAS subsystem203 are integrated together into a single entity.

The base station subsystem 102 includes one or more base transceiverstations (BTSs) 202 that perform baseband processing as discussed aboveon the IP data from the IP network 102 and on the baseband digitalsignals from the DAS subsystem 203. In the example shown in FIG. 1, eachBTS 202 is coupled to an IP access gateway 114 via an IP router 204. TheIP router 204 receives IP data from the IP network 102 (for example,from an IP access gateway 114) and routes the IP data to the appropriateone or more of the BTSs 202. In the upstream, the IP router 204 receivesIP data from the one or more BTSs 202 and provides the IP data to theappropriate entity in the IP network 102. An operations and maintenancemodule 207 can be coupled to the IP router 204.

In an example, each of the BTSs 202 is configured to process a single RFchannel (for example, a 20 MHz channel) supporting multiple users (forexample, 16, 32, or 64 users). In the downstream direction, each BTS 202receives IP data corresponding to its RF channel from the IP router 204.Each BTS 202 performs baseband processing on the IP data from the IPnetwork 102 and places the IP data onto its respective RF channel. EachBTS 202 is configured to output, and receive as input, respectivedigital baseband signals as discussed above. Each BTS 202 generates abaseband digital signal from the IP data, wherein the baseband digitalsignal is a representation of an RF signal at baseband. In an example,the baseband digital signals can conform to a standard for basebanddigital signals, for example, the Open Base Station ArchitectureInitiative (OBSAI) or the common public radio interface (CPRI). In anexample, the baseband digital signals can conform to a proprietaryprotocol. In an example, the BTSs 202 comprise a plurality of home nodeB (HNB) base transceiver stations and/or a plurality of enhanced homenode B (HENB) base transceiver stations. In one implementation of suchan embodiment, each of the plurality of HNB base transceiver stationsimplements at least one third-generation (3G) protocol and/or each ofthe plurality of HENB base transceiver stations implements at least onefourth-generation (4G) protocol.

In an example, the host unit 104 can also include a scheduler 203 tocontrol the BTSs 202. The scheduler 203 can be an integrated part of thehost unit 104 and, as such, is co-located with the BTSs 202. Thescheduler can be coupled to the BTSs 202 via a control interface. In anexample, the scheduler 203 can implement functions of a base stationcontroller to control operation of the BTSs 202. In one implementationof such an embodiment, the scheduler 203 is implemented as a low-latencyjoint scheduler (LUS). In one example, the scheduler 203 implements atleast one of semi-static scheduling and dynamic scheduling.

Each BTSs 202 can provide the baseband digital signals to a basebandinterface (BBIF) 206. The baseband digital interface 202 can provide aninterface between the one or more BTSs 102 and a switching unit 206.Baseband digital signals, as discussed above, can be sent between eachBTS 102 and the switching unit 206. In an example, the BBIF 206 is apassive backplane that the baseband digital signals pass through betweenthe BTS 102 and the switching unit 206.

Switching unit 208 can provide bi-directional conversion betweenmultiple baseband digital signals one or more serial data streams forthe remote units 106. The switching unit 206 can receive from, andoutput to, each BTS 202 respective baseband digital signals. In thedownstream, the switching unit 206 can receive baseband digital signalsfrom the one or more BTSs 206 and provide one or more serial datastreams to the remote units 106. In the upstream, the switching unit 208can receive one or more serial data streams from the remote units 106and provide baseband digital signals to their respective BTSs 202.

In an example, each serial data stream communicated between the hostunit 104 and one or more remote units 106 is formatted into a pluralityof time slots. The time slot can be further organized into words, whereeach word includes a defined number of time slots. In the downstream,the switching unit 208 can format each baseband digital signal into dataformatted for a time slot of a serial data stream. For example, theswitching unit 208 can capture “slices” of a baseband digital signal (arepresentation of an RF channel), where each slice corresponds to the RFsignal during a time period of the corresponding RF channel. Theswitching unit 208 can then format each “slice” into data formatted fora time slot of the one or more serial data streams. In examplesincluding multiple BTSs 102, a plurality of baseband digital signals isprovided to the baseband interface 202 and the switching unit 208 inparallel. The switching unit 208 can capture slices of each of thesebaseband digital signals and convert each into data formatted for a timeslot of the one or more serial data streams.

In addition to BTSs 202, the BBIF 206 can provide an interface forbaseband digital signals from other components. For example, the DASsubsystem 203 can also include one or more digital to analog RFtransceivers (DART) 212. A DART 212 is communicatively coupled to a basestation 107 that is distinct from the host unit 104 via a base stationlink 109. A DART 212 provides bi-directional conversion to/from RFsignals from/to baseband digital signals. In the downstream direction, abase station 107 receives data (e.g., IP data from the IP network 102)corresponding to a RF signal to be transmitted to a wireless device. Thebase station 107 generates the RF signal for transmission to thewireless device. A DART 212 takes as input the RF signal from the basestation 107 and converts the analog signal to a baseband digital signalby taking digital samples of the RF signal. In an example, each DART 212operates on a single RF channel. In the upstream direction a DART 212receives a baseband digital signal from the switch 208, converts it toan RF signal, and sends the RF signal to the base station 107. The basestation 107 can receive the RF signal and perform baseband processingthereon. Accordingly, the signals sent between a base station 107 andthe DART 212 are not IP data as discussed above; instead they are RFsignals and baseband processing is performed by the base station 107.

Each DART 212 is configured to operate on a single RF channel, anddifferent DARTs 212 on different RF channel modules 304 installed in thehost unit 104 can be configured to operate on different channels(frequency bands), use different communication protocols, and/orcorrespond to different service providers'. Each DART 212, however,converts to and from a baseband protocol (for example, the commonbaseband protocol) for the BBIF 206. As an example a first DART 212 canbe configured to operate on 850 MHz cellular transmissions, which asecond DART 212 can be configured to operate on 1900 MHz PCS signals.Some of the other options for a DART 212 include Nextel 800 band, Nextel900 band, PCS full band, PCS half band, BRS, WiMax, LTE, and theEuropean GSM 900, DCS 1800, and UMTS 2100.

In some embodiments, DART 212 is implemented with a DART modulecommercially available from TE Connectivity as part of the ElexWave™line of products. The DART module is also described in U.S. patentapplication Ser. No. 11/627,251, assigned to ADC Telecommunications,Inc., published in U.S. Patent Application Publication No. 2008/0181282,and incorporated herein by reference.

The BBIF 206 can also interface between the switching unit 208 and abaseband protocol adapter 214. The baseband protocol adapter 214 can becommunicatively coupled to a base station 107 via one or more basestation links 109 and can bi-directionally communicate baseband digitalsignals therebetween. In an example, the baseband protocol adapter 214can be configured to convert between a first baseband communicationprotocol used by the base station 107 and a second baseband protocolused by the switching unit 208. In other examples, the baseband protocoladapter 214 can be a passive device that passes baseband digital signalsbetween the base station 107 and the switching unit 208 through the BBIF206.

Although a single DART 212, single baseband protocol adapter 214, andtwo BTSs 202 are shown in FIG. 2, the host unit 104 can include anynumber of DARTs 212, baseband protocol adapters 214 and BTSs 202.Moreover, although the host unit 104 in FIG. 1 is shown as including aDART 212, baseband protocol adapter 214, and (two) BTSs 202, the hostunit 104 need not include each of these types (DART 212, basebandprotocol adapter 214, and BTS 202) of components and can include onlyone or two of these types of components.

In an example, the switching unit 208 can implement a defined, commonbaseband digital signal protocol for the baseband digital signals fromeach BTS 202, DART 212, and baseband protocol adapter 214. That is, theswitching unit 208 can implement a baseband digital signal protocol towhich all BTSs 202, DARTs 212, and baseband protocol adapters 214 of thehost unit 104 conform. The common baseband digital signal protocol canbe one of the standards or a proprietary protocol as discussed above.Using a common baseband digital signal protocol for each BTS 202, DART212, and baseband protocol adapter 214 enables the switching unit 208 tomultiplex signals from a BTSs 102, DARTs 212, and baseband protocoladapters 214 together onto one or more than one serial data stream andsent over the same transport medium to one or more remote units 106.Moreover, the common baseband digital signal protocol can enabledifferent frequency bands, wireless communication protocols, as well asservices from different wireless service providers, to be multiplexedtogether onto one or more serial data streams and sent over the sametransport medium to one or more remote units 106. In such an example,each BTS 102, DART 212, and baseband protocol adapter 214 can provideand receive baseband digital signals conforming to the common basebanddigital signal protocol regardless of the frequency band, communicationprotocol, and/or service. In this way, the DAS 100 can operate onmultiple distinct frequency bands, wireless communication protocols,services, and input types (IP data, RF signals, baseband digitalsignals) concurrently.

In such an example, each BTS 202 can convert between the common basebanddigital signal protocol for the switching unit 208 and IP data for theIP network 102. The DART 212 can convert between RF signals and thecommon baseband digital signal protocol. The baseband protocol adaptercan either pass signals through from a base station 107 that are conformto the common baseband digital signal protocol or can convert betweenbaseband digital signals having a format for the base station 107 andbaseband digital signals conforming to the common baseband digitalsignal protocol.

In other examples, the switching unit 208 is configured to send andreceive baseband digital signals having different baseband digitalsignal protocols with different components (BTS(s) 202, DART(s) 212,baseband protocol adapter(s) 214). In such an example, the switchingunit 208 can be configured to convert between the disparate basebanddigital signal protocols and a common baseband protocol. In anotherembodiment of such an example, the switching unit 208 does not convertthe disparate baseband digital signal protocols and sends and receivesthe disparate baseband digital signal protocols (as serial data streams)to and from the remote units 106.

As mentioned above, the switching unit 208 can multiplex multiplebaseband digital signals (in particular, the data formatted for timeslots generated therefrom) into one or more serial data streams for theremote units 106. In some examples, the parallel baseband digitalsignals from all the BTSs 202, DARTs 212, and baseband protocol adapters214 of the host unit 104 are multiplexed together into a single serialdata stream. In other examples, multiple serial data streams aregenerated, where each serial data stream can correspond to one or moreof the parallel baseband digital signals. For example, the switchingunit 208 can be configured to route each of the baseband digital signalsto a respective subset of the remote units 106. Moreover, there need notbe a one-to-one relationship between a baseband digital signal and aserial data stream. In other words, the switching unit 208 can generatemultiple copies of data formatted for a time slot from one or more ofthe baseband digital signals and place a first copy of the data on afirst serial stream, a second copy of the data on a second serial streamand so on. In this manner, the switching unit 208 can generate one ormore serial data streams, wherein each serial data stream can includedata from any one or more of the BTSs 202, DARTs 212, and basebandprotocol adapters 214. The switching unit 208 can optionally beconfigured to perform protocol conversion between a first basebandprotocol used by a BTS 202, DART 212, or baseband protocol adapter 214and a second baseband protocol used by the plurality of remote units.

In addition to controlling which of the serial data streams data from abaseband digital signal is placed on, the switching unit 208 can alsocontrol which time slot within a given serial data stream that aparticular time slot of data is placed. In an example, each time slot ofthe downstream serial data stream(s) can be allocated to one or moreremote units 106, and the switching unit 208 controls which remote units106 receive which baseband digital signals based on the time slot inwhich the data from the baseband digital signals is placed. For example,if time slots 1-5 of each word of a serial data stream are allocated toa first remote unit 106, the switching unit 208 can place a time slot ofdata from a baseband digital signal corresponding to that remote unit208 into each of time slots 1-5 of a given word.

In some examples the allocation of time slots is controlled by the hostunit 104. In such examples, the switching unit 208 can change (e.g.,add, eliminate, or swap) which remote units 106 that receive data from aparticular baseband digital signal by changing which time slot the datais placed in accordingly. In this way, the switching unit 208 canincrease or decrease capacity for a given remote unit 106 by allocatingmore or fewer slots to the remote unit 106. In other examples, the timeslots for a particular remote unit 106 are not under the control of theswitching unit 208 and, instead, are configured manually. In embodimentsincluding multiple serial data streams, the switching unit 208 can alsocontrol which remote units 106 receive data from a particular basebanddigital signal by controlling which of the multiple serial data streamsreceive the data as discussed above.

Using the above, the switching unit 208 can dynamically control whichremote units 106 receive which baseband digital signals in order tomanage capacity changes over different areas or for other reasons.Moreover, this control is effective for multiple different frequencybands, communication protocols, and/or services concurrently.

In an example, the switching unit 208 is implemented as aspace-frequency switch (SFS). In some embodiments, switching unit 208 isimplemented with a Serialized RF (SeRF board) commercially availablefrom TE Connectivity as part of the FlexWave™ line of products. The SeRFboard is also described in U.S. patent application Ser. No. 11/627,251,assigned to ADC Telecommunications, Inc., published in U.S. PatentApplication Publication No. 2008/0181282, and incorporated herein byreference.

The host unit 104 can also include an electronic-to-optical(E/O)/optical-to-electrical (O/E) converter 210 for converting theserial data stream(s) from the switching unit into an optical signal fortransmission over a fiber optic cable(s) to one or more RAUs 106 and/orintermediary devices 107.

A wavelength division multiplexer (WDM) (not shown) can also be used tomultiplex both the downlink and uplink optical signals onto a singlefiber when only a single optical fiber is used to couple one or more ofthe remote units 106 with the host unit 104.

In the upstream, the 0/E converter 210 can convert optical signals fromthe fiber optic cable(s) into an electrical signal. The serial datastream received from the remote units 106 can be provided to theswitching unit 208. The switching unit 208 can demultiplex the serialdata stream to form multiple baseband digital signals for the BTS(s)202, DART(s) 212, and baseband protocol adapter(s) 214. The switchingunit 208 can route each of a baseband digital signals to a subset of thebase transceiver stations 202, DART(s) 212, and baseband protocoladapter(s) 214. The switching unit 208 can generate multiple parallelbaseband digital signals, one per BTS 202, DART 212, and basebandprotocol adapter 214. In some embodiments, switching unit 208 aggregatesuplink signals associated with a downlink simulcast signal and routesthe aggregated uplink signal to its corresponding BTS 202, DART 212, orbaseband protocol adapter 214. As discussed above, the serial datastream can be formatted into words comprising a plurality of time slots.Each time slot of the upstream serial data stream(s) are allocated to aBTS 202, DART 212, or baseband protocol adapter 214. Accordingly, thebaseband digital signal provided to each BTS 202, DART 212, or basebandprotocol adapter 214 can correspond to the data in the time slots of theupstream serial data stream(s) that are allocated to the particular BTS202, DART 212, or baseband protocol adapter 214.

Similar to the downstream, in some examples switching unit 208 cancontrol the upstream bandwidth of each remote unit 106 based on the timeslots in the upstream serial data stream(s) allocated to the remote unit106. In other examples, the allocation of time slots for a particularremote unit 106 is not under the control of the switching unit 208 and,instead, is configured manually. The upstream baseband digital signalsfrom the switching unit 208 are sent through the baseband interface 206and are received at their respective BTS 202 DART 212, or basebandprotocol adapter 214.

Each BTS 202 processes the received baseband digital signal andgenerates IP data which is sent to the IP router 204. The IP router 204routes the IP data to the appropriate entity in the IP network 102 via abackhaul link 103. Each DART 212 converts its respective basebanddigital signal to an RF signal and sends the RF signal to a base station107 via a base station link 109. Each baseband protocol adapter 214converts the baseband digital signal to another baseband digital signalprotocol or otherwise passes the baseband digital signal to a basestation 107 via a base station link 109.

In one example, the host unit 104 is configured to intercept UE reportsof cell measurements. In one implementation of such an embodiment,wherein the DAS 100 further comprises a measurement receiver in eachremote unit 106 to measure path loss to neighbor remote units. In oneimplementation of such an embodiment, the DAS 100 is configured tomonitor traffic and measurement data passing through the system in orderto estimate traffic load per remote unit and/or traffic load per userdevice. The traffic load estimates can optionally be used by theswitching unit 208.

FIG. 3 is an example diagram of a host unit 104. In the example of FIG.3, the host unit 104 is a modular wireless platform that enables asystem facilitator to easily and inexpensively adapt their wirelesssystem for use with different data transport mechanisms, frequencybands, communication technologies, and intelligence distribution. Thehost unit has a modular design and a baseband interface 206 that allowRF channel modules 304 to be physically installed and removed to adaptto the needs of the service providers. The host is designed around thebaseband interface 206 and a switching unit 208 that can operate withbaseband digital signals corresponding to different frequency bands andcommunication protocols, as well as services from different wirelessservice providers and different RF channel modules 304.

In the example shown in FIG. 3, baseband interface 202 is a passivebackplane including a plurality of BBIF connectors 302 (for example,edge connectors). Each BBIF connector 302 is configured to have insertedtherein an RF channel module 304 and is configured to electricallycouple an inserted RF channel module 304 to the switch 208. In anexample, the RF channel module 304 is a circuit card comprising aprinted circuit board having an appropriate module connector 306 formating with a BBIF connector 302. In an example, the module connector306 is a dual inline edge connector. This enables an RF channel module304 configured for use with the baseband interface 202 to be physicallyinserted and removed from the host unit 104. The RF channel module 304is pluggable and removable and mating a module connector 306 with a BBIFconnector 302 forms a non-permanent electrical connection between the RFchannel module 304 and the BBIF 206. The connection is non-permanent inthat the connection can be made and removed in the field withoutdamaging the module connector 306 or the BBIF connector 302 and theelectrical connection is based on physical contact between conductors onthe module connector 306 and conductors on the BBIF connector 304. Thisnon-permanent connection does not include a connection made with solderor the like or a connection made by physically deforming one or both ofthe connectors, such as when a connector is crimped. The BBIF 206includes multiple BBIF connectors 302 for coupling with multiple RFchannel modules 304. Although five BBIF connectors 302 are shown in FIG.3 it should be understood that other numbers of BBIF connectors 302 canbe included in BBIF 206.

When an RF channel module 304 is inserted into a BBIF connector 302(that is, when the module connector 306 is mated with the BBIF connector304), the RF channel module 304 is electrically coupled to the backplaneand can output signals to, and receive signals from, the switching unit208.

FIG. 3 illustrates four RF channel modules 304 of three different types.One type includes a DART 212 that is coupled to a base station 107 via abase station link 109 as discussed above. Another type of RF channelmodule 304 includes a BTS 202 that is coupled to an IP network 102 via abackhaul link 103 as discussed. Yet another type of RF channel module304 includes a baseband protocol adapter 214 that is coupled to a basestation 107 via a base station link 109. Other types of RF channelmodules 304 may also be used.

As mentioned above, in some examples, the switching unit 208 implementsa common baseband digital signal protocol. In such example, thecomponents (e.g., BTS 202, DART 212, and baseband protocol adapter 214)within the different types of RF channel modules 304 are configured toprovide and receive baseband digital signals with the switching unit 208that conform to the common baseband digital signal protocol as discussedabove. Different types of RF channel modules 304 can be inserted intodifferent BBIF connectors 302 on the BBIF 206 at the same time. Thus,the BBIF 206 and switching unit 208 can inter-operate with differenttypes of RF channel modules 304 concurrently. That is, the host unit 104enables one or more RF channel modules 304 having a DART 212 thereon,one or more RF channel modules 304 having a BTS 202 thereon, and one ormore RF channel modules 304 having a baseband protocol adapter 214thereon can be installed (i.e., connected with the BBIF 206)concurrently. Accordingly, some of the multiple baseband digital signalssent through the BBIF 206 can correspond to a DART 212 that communicateswith a base station 107 that is distinct from the host unit 104, andothers can correspond to a BTS 202 that is integrated into the host unit104. In this way, the host unit 104 is flexible and fieldre-configurable to different frequency bands, communication protocols,service providers', and for integration of a BTS 202 therein.

FIG. 4 is a block diagram of another example host unit 104. In thisexample, the host unit 104 includes a plurality of reconfigurablebaseband modules 402 as the BTSs 202. That is, each reconfigurablebaseband module 402 can be configures as a BTS 202 as described abovewith respect to FIG. 2. Each reconfigurable baseband module 402 includesa processing device 404 coupled to one or more memory devices 406 havinginstructions thereon to cause the processing device 404 to function as aBTS 202. In an example, the instructions can be modified to change theoperation of the reconfigurable baseband module 402, such that thereconfigurable baseband module 402 operates on a different frequencyband, communication protocols, and/or operates on services fromdifferent wireless service providers.

The reconfigurable baseband processors 402 are coupled to the IP router204 over a communication bus 410. In an example, the bus 410 is a serialbus such as a peripheral component interconnect express (PCIE) bus;however, other bus protocols can be used. The reconfigurable basebandmodules 402 are also coupled to the switching unit 208 through the bus410. In addition, one or more DARTs 212 and one or more basebandprotocol adapters 214 can also be coupled to the bus 410 forcommunication with the switching unit 208 and/or other components. TheDART(s) 212 and baseband protocol adapter(s) 214 can function asdescribed above with respect to FIG. 2 by communicating with a basestation 107 through a base station link 109 and the switching unit 208over the bus 410.

In this example, the BBIF 206 is a virtual interface and signals betweenthe reconfigurable baseband module(s) 402, DART(s) 212, and basebandprotocol adapter(s) 214, and the switching unit 208 can comprisebaseband digital signals which, for example, can conform to a commonbaseband protocol. The switching unit 208 can perform switchingoperations as discussed above with respect to FIG. 2 and can communicatewith the 0/E converter 210 over the bus 410 for transmission andreception of signals to remote units 106. Accordingly, the bus 410communicatively couples the reconfigurable baseband processor(s) 402,DART(s) 212, baseband interface adapter 214, IP router 204, and theswitching unit 208 to one another. A system controller and othercomponents can also be coupled to the bus 410.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications to the described embodiments maybe made without departing from the spirit and scope of the claimedinvention.

EXAMPLE EMBODIMENTS

Example 1 includes a distributed antenna system (DAS) comprising: a hostunit; and a plurality of remote units communicatively coupled to thehost unit; wherein the host unit comprises: a plurality of basetransceiver stations; and a switch; wherein each of the base transceiverstation is configured to operate on a radio frequency (RF) channel andwherein each of the base transceiver stations is configured to provide adownstream baseband digital signal to the switch and to receive anupstream baseband digital signal from the switch, wherein eachdownstream baseband digital signal and upstream baseband digital signalis a digital representation of the RF channel at baseband of therespective base transceiver station; wherein the switch is configured toroute each of the downstream baseband digital signals to a respectivesubset of the remote units as one or more downstream serial data streamsand to route each of the upstream baseband digital signals from one ormore upstream serial data streams to a respective subset of the basetransceiver stations.

Example 2 includes the DAS of Example 1, wherein the baseband digitalsignals comprise in-phase digital baseband data and quadrature digitalbaseband data.

Example 3 includes the DAS of any of Examples 1 or 2, wherein each ofthe base transceiver stations is configured to receive downstreamInternet Protocol (IP) data and perform baseband processing on thedownstream IP data to generate the downstream baseband digital signal,and to receive an upstream digital baseband signal and perform basebandprocessing on the upstream baseband digital signal to generate IP data.

Example 4 includes the DAS of any of Examples 1-3, wherein each of thebase transceiver stations is coupled to an Internet Protocol (IP) accessgateway that controls access to a carrier network.

Example 5 includes the DAS of any of Examples 1-4, wherein the host unitcomprises a baseband interface to interface between the plurality ofbase transceiver stations and the switch, wherein the switch isconfigured to implement a common baseband communication protocol foreach of the base transceiver stations.

Example 6 includes the DAS of example 5, wherein the common basebandcommunication protocol conforms to one the Open Base StationArchitecture Initiative (OBSAI) or the common public radio interface(CPRI).

Example 7 includes the DAS of any of Examples 1-6, wherein the host unitcomprises a baseband interface to interface between the plurality ofbase transceiver stations and the switch, wherein the baseband interfaceis a backplane including a plurality of baseband interface connectors,wherein each base transceiver station is disposed on a circuit cardhaving a module connector that is mated with one of the basebandinterface connectors.

Example 8 includes the DAS of Example 7, wherein the host unit includes:a digital-to-analog RF transceiver (DART) configured to convert betweenRF signals and digital baseband signals, wherein the DART is disposed ona circuit card having a module connector that is mated with one of thebaseband interface connectors.

Example 9 includes the DAS of any of Examples 7 or 8, wherein the hostunit includes: a baseband protocol adapter configured to interfacebetween a baseband digital signal of a base station and the basebandinterface, wherein the baseband protocol adapter is disposed on acircuit card having a module connector that is mated with one of thebaseband interface connectors.

Example 10 includes the DAS of any of Examples 1-9, where the host unitincludes a communication bus; wherein each base transceiver station isimplemented in a reconfigurable baseband module and wherein eachreconfigurable baseband module is coupled to the communication bus;wherein the switch is coupled to the communication bus.

Example 11 includes the DAS of any of Examples 1-10, wherein the basetransceiver stations comprise a plurality of home node B (HNB) basetransceiver stations and/or a plurality of enhanced home node B (HENB)base transceiver stations.

Example 12 includes the DAS of any of Examples 1-11, wherein each of theplurality of HNB base transceiver stations implements at least onethird-generation (3G) protocol and/or each of the plurality of HENB basetransceiver stations implements at least one fourth-generation (4G)protocol.

Example 13 includes the DAS of any of Examples 1-12, wherein the DAS isconfigured for use with licensed radio frequency spectrum (including,but not limited to, cellular licensed radio frequency spectrum).

Example 14 includes the DAS of any of Examples 1-13, wherein the DAS isconfigured for use with unlicensed radio frequency spectrum (including,but not limited to, IEEE 802.11 radio frequency spectrum).

Example 15 includes the DAS of any of Examples 1-14, wherein the systemis configured for use with a MIMO protocol.

Example 16 includes the DAS of any of Examples 1-15, wherein the DAS isconfigured for use in at least one of: in-building applications, outdoorapplications, enterprise applications, public safety applications, andmilitary applications.

Example 17 includes the DAS of any of Examples 1-16, wherein groups ofthe remote units are configurable for local joint beamforming and/orjoint transmission groups of cell.

Example 18 includes a distributed antenna system (DAS) comprising: ahost unit; and a plurality of remote units communicatively coupled tothe host unit; wherein the host unit comprises: a baseband interfacebackplane having a plurality of backplane connectors, each backplaneconnector configured for insertion of a radio frequency (RF) channelmodule; a switch configured to convert between one or more serial datastreams for the remote units and baseband digital signals, wherein thebaseband digital signals comprise a digital representation of an RFchannel at baseband; a first RF channel module inserted into a first ofthe backplane connectors, the first RF channel module including adigital-to-analog RF transceiver to convert between an RF signal of abase station and a baseband digital signal; and a second RF channelmodule inserted into a second of the backplane connectors, the second RFchannel module including a base transceiver station configured toreceive downstream Internet Protocol (IP) data and perform basebandprocessing on the downstream IP data to generate the downstream basebanddigital signal, and to receive an upstream digital baseband signal andperform baseband processing on the upstream baseband digital signal togenerate IP data.

Example 19 includes the DAS of Example 18, wherein the host unitcomprises: a third RF channel module inserted into a third of thebackplane connectors, the third RF channel module including a basebandprotocol adaptor configured to convert between a baseband protocol of abase station and a baseband protocol of baseband interface backplane.

Example 20 includes the DAS of any of Examples 18 or 19, wherein thebaseband interface backplane and the switch are configured to implementa common baseband communication protocol for each RF channel module.

Example 21 includes the DAS of Example 20, wherein the common basebandcommunication protocol conforms to one the Open Base StationArchitecture Initiative (OBSAI) or the common public radio interface(CPRI).

Example 22 includes the DAS of any of Examples 18-21, wherein thebaseband digital signals comprises in-phase digital baseband data andquadrature digital baseband data.

Example 23 includes the DAS of any of Examples 18-22, wherein the basetransceiver station of the second RF module is coupled to an InternetProtocol (IP) access gateway that controls access to a carrier network.

Example 24 includes the DAS of any of Examples 18-23, wherein the basetransceiver station comprises one of a home node B (HNB) basetransceiver station or an enhanced home node B (HENB) base transceiverstation.

Example 25 includes the DAS of any of Examples 18-24, wherein the basetransceiver station comprises a HNB base transceiver stations thatimplements at least one third-generation (3G) protocol, or the basetransceiver station comprises a HENB base transceiver station thatimplements at least one fourth-generation (4G) protocol.

Example 26 includes the DAS of any of Examples 18-25, wherein the DAS isconfigured for use with licensed radio frequency spectrum (including,but not limited to, cellular licensed radio frequency spectrum).

Example 27 includes the DAS of any of Examples 18-26, wherein the DAS isconfigured for use with unlicensed radio frequency spectrum (including,but not limited to, IEEE 802.11 radio frequency spectrum).

Example 28 includes the DAS of any of Examples 18-27, wherein the systemis configured for use with a MIMO protocol.

Example 29 includes the DAS of any of Examples 18-28, wherein the DAS isconfigured for use in at least one of: in-building applications, outdoorapplications, enterprise applications, public safety applications, andmilitary applications.

Example 30 includes the DAS of any of Examples 18-29, wherein groups ofthe remote units are configurable for local joint beamforming and/orjoint transmission groups of cells.

Example 31 includes a method for generating and distributing wireless RFsignals at a host unit in a distributed antenna system comprising thehost unit which is communicatively coupled to a plurality of remoteunits, the method comprising: receiving Internet Protocol (IP) data atthe host unit, from an IP network entity, wherein the IP datacorresponds to a radio frequency (RF) signal; routing the IP data to arespective base transceiver station within the host unit; at the hostunit, baseband processing the IP data at each base transceiver stationsuch that each base transceiver station generates a digitalrepresentation of an RF signal for transmission from a remote unit to awireless device, wherein the digital representation of the RF signal isat baseband; at the host unit, multiplexing the digital representationsof an RF signal together to form a serial data stream; and sending theserial data stream from the host unit to one or more of the remoteunits.

Example 32 includes the method of Example 31, wherein digitalrepresentations of RF signals comprise comprises in-phase digitalbaseband data and quadrature digital baseband data.

Example 33 includes the method of any of Examples 31 or 32, comprising:receiving at the host unit a serial data stream from one or more remoteunits; demultiplexing the serial data stream to form a plurality ofbaseband digital signals, each baseband digital signal is a digitalrepresentation of an RF channel at baseband; routing each of thebaseband digital signals to a base transceiver station within the hostunit such that each baseband digital signal is sent to a basetransceiver station that processes the RF channel of that basebanddigital signal; processing each baseband digital signal to generate IPdata corresponding thereto; and sending the IP data from the host unitto an entity the IP network entity.

Example 34 includes the method of any of Examples 31-33, wherein the IPnetwork entity is an IP access gateway that controls access to a carriernetwork.

Example 35 includes the method of any of Examples 31-34, wherein theswitch is configured to implement a common baseband communicationprotocol for each of the base transceiver stations.

Example 36 includes the method of Example 35, wherein the commonbaseband communication protocol conforms to one the Open Base StationArchitecture Initiative (OBSAI) or the common public radio interface(CPRI).

Example 37 includes the method of any of Examples 31-36 comprising:converting between an RF signal from a base station and a second digitalrepresentation of the RF signal, wherein multiplexing includesmultiplexing the second digital representation of the RF signal togetherwith the digital representations of an RF signal from the IP data.

Example 38 includes the method of any of Examples 31-37, whereinbaseband processing the IP data at each base transceiver stationincludes baseband processing as a home node B (HNB) base transceiverstation and/or an enhanced home node B (HENB) base transceiver station.

Example 39 includes the method of Example 38, wherein basebandprocessing the IP data implements at least one third-generation (3G)protocol and/or each of the plurality of EHNB base transceiver stationsimplements at least one fourth-generation (4G) protocol.

1. A distributed antenna system (DAS) comprising: a host unit; and aplurality of remote units communicatively coupled to the host unit;wherein the host unit comprises: a plurality of base transceiverstations; and a switch; wherein each of the base transceiver station isconfigured to operate on a radio frequency (RF) channel and wherein eachof the base transceiver stations is configured to provide a downstreambaseband digital signal to the switch and to receive an upstreambaseband digital signal from the switch, wherein each downstreambaseband digital signal and upstream baseband digital signal is adigital representation of the RF channel at baseband of the respectivebase transceiver station; wherein the switch is configured to route eachof the downstream baseband digital signals to a respective subset of theremote units as one or more downstream serial data streams and to routeeach of the upstream baseband digital signals from one or more upstreamserial data streams to a respective subset of the base transceiverstations.
 2. The DAS of claim 1, wherein the baseband digital signalscomprise in-phase digital baseband data and quadrature digital basebanddata.
 3. The DAS of claim 1, wherein each of the base transceiverstations is configured to receive downstream Internet Protocol (IP) dataand perform baseband processing on the downstream IP data to generatethe downstream baseband digital signal, and to receive an upstreamdigital baseband signal and perform baseband processing on the upstreambaseband digital signal to generate IP data.
 4. The DAS of claim 1,wherein each of the base transceiver stations is coupled to an InternetProtocol (IP) access gateway that controls access to a carrier network.5. The DAS of claim 1, wherein the host unit comprises a basebandinterface to interface between the plurality of base transceiverstations and the switch, wherein the switch is configured to implement acommon baseband communication protocol for each of the base transceiverstations.
 6. The DAS of claim 5, wherein the common basebandcommunication protocol conforms to one the Open Base StationArchitecture Initiative (OBSAI) or the common public radio interface(CPRI).
 7. The DAS of claim 1, wherein the host unit comprises abaseband interface to interface between the plurality of basetransceiver stations and the switch, wherein the baseband interface is abackplane including a plurality of baseband interface connectors,wherein each base transceiver station is disposed on a circuit cardhaving a module connector that is mated with one of the basebandinterface connectors.
 8. The DAS of claim 7, wherein the host unitincludes: a digital-to-analog RF transceiver (DART) configured toconvert between RF signals and digital baseband signals, wherein theDART is disposed on a circuit card having a module connector that ismated with one of the baseband interface connectors.
 9. The DAS of claim7, wherein the host unit includes: a baseband protocol adapterconfigured to interface between a baseband digital signal of a basestation and the baseband interface, wherein the baseband protocoladapter is disposed on a circuit card having a module connector that ismated with one of the baseband interface connectors.
 10. The DAS ofclaim 1, where the host unit includes a communication bus; wherein eachbase transceiver station is implemented in a reconfigurable basebandmodule and wherein each reconfigurable baseband module is coupled to thecommunication bus; wherein the switch is coupled to the communicationbus.
 11. The DAS of claim 1, wherein the base transceiver stationscomprise a plurality of home node B (HNB) base transceiver stationsand/or a plurality of enhanced home node B (HENB) base transceiverstations.
 12. The DAS of claim 1, wherein each of the plurality of HNBbase transceiver stations implements at least one third-generation (3G)protocol and/or each of the plurality of HENB base transceiver stationsimplements at least one fourth-generation (4G) protocol.
 13. The DAS ofclaim 1, wherein the DAS is configured for use with licensed radiofrequency spectrum (including, but not limited to, cellular licensedradio frequency spectrum).
 14. The DAS of claim 1, wherein the DAS isconfigured for use with unlicensed radio frequency spectrum (including,but not limited to, IEEE 802.11 radio frequency spectrum).
 15. The DASof claim 1, wherein the system is configured for use with a MIMOprotocol.
 16. The DAS of claim 1, wherein the DAS is configured for usein at least one of: in-building pplications, outdoor applications,enterprise applications, public safety applications, and militaryapplications.
 17. The DAS of claim 1, wherein groups of the remote unitsare configurable for local joint beamforming and/or joint transmissiongroups of cells.
 18. A distributed antenna system (DAS) comprising: ahost unit; and a plurality of remote units communicatively coupled tothe host unit; wherein the host unit comprises: a baseband interfacebackplane having a plurality of backplane connectors, each backplaneconnector configured for insertion of a radio frequency (RF) channelmodule; a switch configured to convert between one or more serial datastreams for the remote units and baseband digital signals, wherein thebaseband digital signals comprise a digital representation of an RFchannel at baseband; a first RF channel module inserted into a first ofthe backplane connectors, the first RF channel module including adigital-to-analog RF transceiver to convert between an RF signal of abase station and a baseband digital signal; and a second RF channelmodule inserted into a second of the backplane connectors, the second RFchannel module including a base transceiver station configured toreceive downstream Internet Protocol (IP) data and perform basebandprocessing on the downstream IP data to generate the downstream basebanddigital signal, and to receive an upstream digital baseband signal andperform baseband processing on the upstream baseband digital signal togenerate IP data.
 19. The DAS of claim 18, wherein the host unitcomprises: a third RF channel module inserted into a third of thebackplane connectors, the third RF channel module including a basebandprotocol adaptor configured to convert between a baseband protocol of abase station and a baseband protocol of baseband interface backplane.20. The DAS of claim 18, wherein the baseband interface backplane andthe switch are configured to implement a common baseband communicationprotocol for each RF channel module.
 21. The DAS of claim 20, whereinthe common baseband communication protocol conforms to one the Open BaseStation Architecture Initiative (OBSAI) or the common public radiointerface (CPRI).
 22. The DAS of claim 18, wherein the baseband digitalsignals comprises in-phase digital baseband data and quadrature digitalbaseband data.
 23. The DAS of claim 18, wherein the base transceiverstation of the second RF module is coupled to an Internet Protocol (IP)access gateway that controls access to a carrier network.
 24. The DAS ofclaim 18, wherein the base transceiver station comprises one of a homenode B (HNB) base transceiver station or an enhanced home node B (HENB)base transceiver station.
 25. The DAS of claim 18, wherein the basetransceiver station comprises a HNB base transceiver stations thatimplements at least one third-generation (3G) protocol, or the basetransceiver station comprises an HENB base transceiver station thatimplements at least one fourth-generation (4G) protocol.
 26. A methodfor generating and distributing wireless RF signals at a host unit in adistributed antenna system comprising the host unit which iscommunicatively coupled to a plurality of remote units, the methodcomprising: receiving Internet Protocol (IP) data at the host unit, froman IP network entity, wherein the IP data corresponds to a radiofrequency (RF) signal; routing the IP data to a respective basetransceiver station within the host unit; at the host unit, basebandprocessing the IP data at each base transceiver station such that eachbase transceiver station generates a digital representation of an RFsignal for transmission from a remote unit to a wireless device, whereinthe digital representation of the RF signal is at baseband; at the hostunit, multiplexing the digital representations of an RF signal togetherto form a serial data stream; and sending the serial data stream fromthe host unit to one or more of the remote units.
 27. The method ofclaim 26, wherein digital representations of RF signals comprisecomprises in-phase digital baseband data and quadrature digital basebanddata.
 28. The method of claim 26, comprising: receiving at the host unita serial data stream from one or more remote units; demultiplexing theserial data stream to form a plurality of baseband digital signals, eachbaseband digital signal is a digital representation of an RF channel atbaseband; routing each of the baseband digital signals to a basetransceiver station within the host unit such that each baseband digitalsignal is sent to a base transceiver station that processes the RFchannel of that baseband digital signal; processing each basebanddigital signal to generate IP data corresponding thereto; and sendingthe IP data from the host unit to an entity the IP network entity. 29.The method of claim 26, wherein the IP network entity is an IP accessgateway that controls access to a carrier network.